Ultrasonic Metering of Gas Flows

The large acoustic impedance mismatch between gases and conventional ultrasonic transducers has precluded the commercial ultrasonic metering of gas flow. This hurdle has been overcome by the invention of a low-impedance transducer which is also reported at this conference. This paper describes the development of a sequential-pulse, transit-time, ultrasonic flowmeter based on the low-impedance transducer. The flowmeter offers significant advantages over current domestic gas meters in size, accuracy, turn-down ratio and compatibility with new meter reading technologies. Natural gas flowrates ranging from 0.013 to 8 m3/h have been measured accurately at temperatures ranging from -13 to 47°C.